The relationship between hormone receptors and adenylate cyclase is to be explored in cultured cell systems, including hybrid somatic cells and mutant cell clones that are deficient in specific portions of the responding system. The response system for catecholamines will be assessed be determination of binding of I125 iodohydroxybenzylpindolol as a marker of the Beta adrenergic receptor. Adenylate cyclase activity and the effects and binding of selected guanine nucleotides will also be studied. Similarly, the binding of (H3) PGE1 to specific high affinity sites linked to adenylate cyclase will be evaluated under a variety of conditions to determine the relationship between receptor and catalytic activity. If feasible, solubilization, partial purification, and reconstitution of relevant components of the system will be attempted. BIBLIOGRAPHIC REFERENCES: Sturgill, T.W., Schrier, B.K., and Gilman, A.G. Stimulation of cyclic AMP accumulation by 2-chloroadenosine: Lack of incorporation of nucleoside into cyclic nucleotides. J. Cyclic Nucleotide Res. 1: 21-30, 1975. Maguire, M.E., Sturgill, T.W., Anderson, H.J., Minna, J.D., and Gilman, A.G. Hormonal control of cyclic AMP metabolism in parental and hybrid somatic cells. Adv. Cyclic Nucleotide Res. V, pp. 699-718 (1975).